The field of this invention is cardiac bypass surgery and cardiopulmonary bypass.
During cardiac surgery for procedures such as coronary artery bypass grafting, heart valve repair or replacement, septal defect repair, pulmonary thrombectomy, atherectomy, aneurysm repair, aortic dissection repair and correction of congenital defects, cardiopulmonary bypass and cold cardiac ischemic arrest are often required. Typically, a cooled cardioplegia solution, a solution containing elevated levels of potassium, for example, is administered in the antegrade direction (in the direction of normal blood flow) through the patient""s aorta and into the coronary arteries. The cold (2 to 3 degrees centigrade) cardioplegia solution stops the heart from beating and reduces its temperature to minimize damage to the heart during surgery. The cardioplegia solution exits the coronary circulation through the coronary veins at the coronary sinus, where it empties into the right atrium. Cardiopulmonary bypass maintains the peripheral circulation of oxygenated blood to all body organs except the heart during the period of cold, cardioplegic, ischemic arrest.
For some patients, such as those suffering from critical coronary artery stenosis and aortic valve disease, antegrade perfusion may be difficult, inefficient and incomplete. Retrograde (in the direction opposite of normal blood flow) cardioplegia, using current technology, may be administered via the coronary sinus into the coronary circulation using devices, which cannulate the coronary sinus. Such cannulation of the coronary sinus by prior art devices requires inserting a catheter into the coronary sinus and perfusing cardioplegia into the sinus. Drainage of cardioplegia solution is accomplished into the coronary ostea located at the base of the aorta. The problem with prior art methods is that either the right or left heart will be perfused, but not both, since the right coronary veins come off the coronary sinus at an angle and are not cannulated by current catheters that cannulate the left coronary veins. Thus, incomplete perfusion of segments of the heart muscle, primarily the right heart and septum, will occur since the right coronary veins frequently come off near the coronary sinus ostea or within the right atrial wall proper. The right coronary veins are not perfused by prior art retrograde cardioplegic catheters.
Currently surgeons performing cardiac bypass surgery use one or more cannulae for venous drainage and an additional cannula for retrograde perfusion. The multiple cannulae are obstacles and restrict visibility in the surgical arena. Placement of the cardioplegia cannula into the coronary sinus is a semi-blind procedure performed through an additional purse-string suture-closed access port via the right atrium. The retrograde cannula may be improperly positioned within the coronary sinus, which results in critical coronary vessels being inadequately perfused. Typically, placement of currently available retrograde cardioplegia cannula within the coronary sinus results in retrograde perfusion of the left heart but inadequate retrograde perfusion of the right heart because of cannula obstruction of the right coronary ostea as they arise from the coronary sinus. Thus the tissue of the left heart is perfused, in a retrograde direction, with cardioplegia solution but the right heart is perfused with a diminished, or no, supply of cardioplegia solution since the right coronary veins are generally a side-branch of the left coronary veins at the coronary sinus and the right coronary veins are blocked by the cannula. Poor right heart retrograde perfusion occurs because, most-frequently, anatomic variations of the right coronary sinus and veins cannot be properly perfused with the currently available cannula.
New devices and methods are needed, which facilitate cold cardioplegic arrest, yet limit the number of cannulae required to isolate the heart and coronary blood vessels from the peripheral vasculature, arrest the heart, protect all the coronary blood vessels, protect all or most of the myocardium, and drain venous blood from the inferior and superior vena cava. Furthermore, it would be advantageous to the diseased myocardium being subjected to ischemic arrest if a retrograde cardioplegia perfusion cannula could perfuse the coronary vasculature of both the right and left heart simultaneously.
This invention relates to a balloon, or tourniqueted, catheter or cannula useful in the retrograde administration of cardioplegia through the coronary sinus and simultaneous venous drainage during cardiac bypass surgery without the need to cannulate the coronary sinus.
The invention is a cannula for performing venous drainage and retrograde perfusion of the heart during cardiac bypass surgery. A single multi-lumen cannula of the present invention can perform the same function as multiple cannulae currently used. The cannula of the invention for cardioplegic administration can improve the protection of a heart during periods of ischemia such as occurs during open-heart surgery. The cannula is preferably fabricated from materials, which are biocompatible for the intended use.
One embodiment of the invention is a multi-lumen cannula with occlusive structures for the superior and inferior vena cava, a protection structure, cardioplegia infusion channel, a pressure monitoring port, and venous drainage ports. Occlusion structures may include devices such as, but not limited to, balloons, umbrellas, structures that draw a vacuum against a wall of the heart, externally applied tourniquets, umbrellas with rim-seal balloons, or the like. In a preferred embodiment, the occlusion structures are balloons constructed of elastomeric materials or vacuum-assisted walled structures.
In one embodiment, a first lumen of the cannula is connected to the cardioplegia infusion system and provides cardioplegia solution to arrest the heart. A second cannula lumen is connected to the venous drainage system. The drainage ports are located in the second lumen. A third lumen is connected to the balloon inflation system, which provides inflation fluids, such as water, isotonic saline or cardioplegia solution, under controlled pressure or volume to inflate the occlusion balloons. The pressure of the occlusion balloons and right atrium may also be monitored through additional lumens. The occlusion balloons isolate the heart from the peripheral vasculature by occluding the inferior and superior vena cava just proximal to the right atrium. The inferior and superior vena cava balloons utilized to direct flow into the extracorporeal circuit are optionally movable to accommodate anatomic variability. Additional lumens may be utilized for inflation of multiple balloons, pressure monitoring, flow monitoring, drainage of cardioplegia, fluid and drug infusion and the like. Since it is useful to measure cardioplegic perfusion pressure, a pressure transducer or pressure measuring lumen may, for example, be provided at or near the distal end of the cardioplegia perfusion lumen for this purpose.
The cannula may be placed into the vena cava, for example, via a route through the internal jugular vein, cranial vena cava, femoral vein, or brachial vein. A smaller diameter cannula may be placed through any of the smaller venous access ports. The use of smaller venous access ports may be enabled by use of a pump or vacuum powered venous drainage system, typically external to the cannula. In one embodiment, the catheter or cannula combines the functions of several catheters currently used in cardiac surgery. A single catheter, rather than multiple catheters, facilitates the surgery and improves the surgical field because extra cannulae do not obstruct the operative field. In addition, the number of individual catheters is reduced, providing a more cost effective method for cardiac surgery. Most importantly, improved cardiac protection is achieved compared to that of standard retrograde perfusion cannulae.
In yet another embodiment, a single-function venous drainage cannula comprising occlusion balloons, a cannula, a drainage lumen and ports, and a balloon inflation lumen and ports is provided for access through any percutaneous access point and is routed to the right atrium through the venous system. This embodiment would be very useful for emergency cardiac assist.
The cannula of the present invention provides for venous drainage and simultaneous retrograde cardioplegia delivery into the coronary sinus of the heart so that the myocardium of both the right and left heart is perfused. In doing so, the coronary sinus is pressurized. Optionally, some or all of the right atrium is pressurized. Since such pressurization is unnatural for the thin walls of the right atrium, the catheter or cannula, in one embodiment, provides structures that protect the walls of the right atrium from the high perfusion pressures and minimize the risk of wall rupture. These protective structures include double wall balloons that inflate to approximate the interior of the right atrium. The space between the inner wall and the outer wall is ribbed or channeled so that gaps are maintained when a vacuum is drawn in the space between the outer wall and the inner wall of the balloon. The vacuum is drawn through the cannula by a vacuum applied at the proximal end of the cannula by way of a connector. The venous drainage cannula runs through the center of the balloon and allows for venous blood drainage from both the superior and inferior vena cava. The balloon further comprises a walled off region that is disposed laterally relative to the venous drainage cannula and permits pressurization of the coronary sinus with cardioplegia solution which is introduced at the proximal end of the cannula and which flows through a lumen in the cannula to reach the walled-off region. In one embodiment, the protection structure eliminates the need for the occlusive balloons in the vena cava.
In yet another embodiment, the balloon does not require pulling a vacuum but simply inflates to seal off or isolate the walls of the vena cava relative to the walled-off region in which pressurized cardioplegia solution is infused. Seals or gaskets are provided to ensure that such pressure seal is optimized. In yet another embodiment, the vacuum system further comprises an external collection reservoir and plumbing that returns any blood or bodily fluids captured by the vacuum system, to the external cardiopulmonary circuit.
Since the cardioplegia cannula does not cannulate the coronary sinus, it will perfuse both the left and right side of the heart. Perfusion of the right heart may be very important in obtaining optimal patient outcomes following cardiopulmonary bypass. In addition, cold cardioplegic solution will bathe the endomyocardium of the right ventricle aiding in myocardial protection of the right heart.
In one embodiment, a venous cannula is adapted for retrograde administration of cardioplegia solution to a heart and simultaneous venous drainage from a vena cava during cardiopulmonary bypass comprising a cardioplegia solution infusion mechanism, wherein the cardioplegia solution infusion mechanism receives pressurized cardioplegia solution and routes the pressurized cardioplegia solution into a coronary sinus, located in a right atrium of a heart, without cannulating the coronary sinus. The venous cannula further comprises a venous blood drainage mechanism, wherein the venous blood drainage mechanism drains venous blood from a superior and an inferior vena cava. The cannula further comprises a vena cava occlusion mechanism, wherein the vena cava occlusion mechanism occludes the vena cava from the right atrium to prevent pressurized cardioplegia solution from entering the vena cava. The venous cannula further comprises a protection device, wherein the protection device limits pressurization of the right atrium by the pressurized cardioplegia solution.
One aspect of the invention is a method of cannulating a patient""s heart during cardiopulmonary bypass comprising the steps of inserting a cannula into a venous system of a patient and then positioning the cannula so that said cannula traverses a right atrium and extends into both a superior and an inferior vena cava. The method further comprises enabling an occlusion device in each of the superior and inferior vena cava and draining venous blood from the vena cava. The method further comprises inflating a protection balloon within the right atrium and infusing cardioplegia solution, in the retrograde direction, into a coronary sinus of the heart, without cannulating the coronary sinus, wherein the cardioplegia solution is infused through the cannula into the coronary sinus.
In another embodiment of the invention, a venous cannula is adapted for retrograde administration of cardioplegia solution to a heart during cardiopulmonary bypass and comprises a length of axially elongate multi-lumen tubing with a proximal end and a distal end, wherein at least one of the lumens is a cardioplegia solution infusion lumen, and a cardioplegia solution infusion annulus located near the distal end of the multi-lumen tubing the infusion annulus being operably connected to the cardioplegia solution infusion lumen. The venous cannula further comprises an annular seal ring surrounding the cardioplegia solution infusion annulus, wherein a vacuum lumen in the multi-lumen tubing is operably connected to the annular seal ring. The venous cannula also comprises a cardioplegia solution infusion mechanism, wherein the cardioplegia solution infusion mechanism receives pressurized cardioplegia solution from an external cardioplegia solution infusion source and delivers it to the cardioplegia solution infusion lumen.
For purposes of summarizing the invention, certain aspects, advantages and novel features of the invention are described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.
These and other objects and advantages of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings.